Track type vehicles commonly use a recoil mechanism to relieve excessive stresses in the track system when foreign material is ingested between the track and the idler and/or drive wheels. Most of such recoil mechanisms use a stiff recoil spring which resiliently resists movement of the idler wheel toward the drive wheel but which will permit such movement of the idler wheel if the force acting on the idler wheel is sufficient to overcome the bias of the recoil spring.
The idler wheel of the majority of such track type vehicles is rotatably carried by mounting brackets slidably mounted to the track roller frame. The idler wheel thus moves in a rectilinear path against the force of the recoil spring in a one-to-one relationship such that movement of the idler wheel results in an equal amount of compression of the spring. The tension in the track progressively increases during recoil due to the increasing bias of the recoil spring as it becomes progressively compressed. Thus the track roller frame, bearings, and related supporting structure must be designed to accommodate such excessive internal stresses generated therein. This results in a more massive and heavier components.
U.S. Pat. No. 3,899,218 which issued to Blomstrom, et al on Aug. 12, 1975 discloses a track mechanism in which the idler wheel is swingably mounted to an idler wheel support having one end pivotally connected to the frame and the other end conncected to the recoil mechanism through an elongate link. Technically, that mechanism provides a small degree of variability in the effective movement arm during recoil of the idler wheel against the recoil spring. However, the change in the effective movement arm is so small, no noticeable benefit is derived therefrom in relieving the excessive stresses in the track chain and related structure during recoil. Thus, that mechanism would not solve the problem of excessive forces generated in the mechanism during recoil.
The present invention is directed to overcoming one or more of the problems as set forth above.